Accessing an Elasticsearch Cluster Using Go

Preparations

• The CSS cluster is available.
• Ensure that the server running Go can communicate with the CSS cluster.
• Ensure that Go has been installed on the server. You can download Go from the official website: https://go.dev/dl/.

Connecting to a Non-Security Mode Cluster

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17package main

import (
	"github.com/elastic/go-elasticsearch/v7"
	"log"
)

func main() {
	cfg := elasticsearch.Config{
		Addresses: []string{
			"http://HOST:9200/",
		},
	}

	es, _ := elasticsearch.NewClient(cfg)
	log.Println(es.Info())
}

Connecting to a Security-Mode Cluster

• Connect to a security-mode cluster with HTTPS disabled. The sample code is as follows:

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  19package main
  
  import (
  	"github.com/elastic/go-elasticsearch/v7"
  	"log"
  )
  
  func main() {
  	cfg := elasticsearch.Config{
  		Addresses: []string{
  			"http://HOST:9200/",
  		},
  		Username: "USERNAME",
  		Password: "PASSWORD",
  	}
  
  	es, _ := elasticsearch.NewClient(cfg)
  	log.Println(es.Info())
  }
  
  

• Connect to a security cluster that has enabled HTTPS and does not use certificates. The sample code is as follows:

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  26package main
  
  import (
  	"crypto/tls"
  	"github.com/elastic/go-elasticsearch/v7"
  	"log"
  	"net/http"
  )
  
  func main() {
  	cfg := elasticsearch.Config{
  		Addresses: []string{
  			"https://HOST:9200/",
  		},
  		Username: "USERNAME",
  		Password: "PASSWORD",
  		Transport: &http.Transport{
  			TLSClientConfig: &tls.Config{
  				InsecureSkipVerify: true,
  			},
  		},
  	}
  
  	es, _ := elasticsearch.NewClient(cfg)
  	log.Println(es.Info())
  }
  
  

• Connect to a security cluster that has enabled HTTPS and uses certificates. The sample code is as follows:

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  58package main
  
  import (
  	"crypto/tls"
  	"crypto/x509"
  	"flag"
  	"github.com/elastic/go-elasticsearch/v7"
  	"io/ioutil"
  	"log"
  	"net"
  	"net/http"
  	"time"
  )
  
  func main() {
  	insecure := flag.Bool("insecure-ssl", false, "Accept/Ignore all server SSL certificates")
  	flag.Parse()
  
  	// Get the SystemCertPool, continue with an empty pool on error
  	rootCAs, _ := x509.SystemCertPool()
  	if rootCAs == nil {
  		rootCAs = x509.NewCertPool()
  	}
  
  	// Read in the cert file
  	certs, err := ioutil.ReadFile("/tmp/CloudSearchService.cer")
  	if err != nil {
  		log.Fatalf("Failed to append %q to RootCAs: %v", "xxx", err)
  	}
  
  	// Append our cert to the system pool
  	if ok := rootCAs.AppendCertsFromPEM(certs); !ok {
  		log.Println("No certs appended, using system certs only")
  	}
  
  	config := elasticsearch.Config{
  		Addresses: []string{
  			"https://HOST:9200/",
  		},
  		Username: "USERNAME",
  		Password: "PASSWORD",
  		Transport: &http.Transport{
  			MaxIdleConnsPerHost:   10,
  			ResponseHeaderTimeout: time.Second,
  			DialContext: (&net.Dialer{
  				Timeout:   30 * time.Second,
  				KeepAlive: 30 * time.Second,
  			}).DialContext,
  			TLSClientConfig: &tls.Config{
  				InsecureSkipVerify: *insecure,
  				RootCAs:            rootCAs,
  			},
  		},
  	}
  	es, _ := elasticsearch.NewClient(config)
  	log.Println(elasticsearch.Version)
  	log.Println(es.Info())
  }
  
  

Running Code

go env -w GO111MODULE=on
go env -w GOPROXY=https://goproxy.io,direct 
go env -w GONOSUMDB=*

go mod init test
go mod tidy
go run EsTest.go